MP4 video import error

Storyline 360 video import of an MP4 output from Camtasia 3 suddenly stopped working. I first get the error report message shown in attachment 1. Then the application doesn't actually close, but a small "video" patch appears, as shown in attachment 2. I tried "change video," closing and reopening the project, but same result. The specs for the MP4 video, shown in attachment 3,  seem straight forward enough - and I was using Camtasia 2 MP4 output previously without a problem. Ugh.

Under tight deadline - appreciate any help or guidance, thanks!